I asked the BB CC about this issue, they really don't know about this rate and saying simply they can't change the Upstream rate, and they said ' You will get only download speed as we mentioned in the tarrif"

So, can some one reply an solution for this issue ? How to change the upstream rate in my MODEM ? Waiting for your replies .

ADSL upload speed for BSNL is 768 kbps, but at times it can increase slightly more but will not top 1mbps. Most probably it is your line issue. You can talk to helpdesk/local tel exchange to solve it most of the time.